YABU. Blogs have been a huge help to me in the last year or so. I have an unusual medical condition that required major and really rather risky surgery this summer. Learning to walk again is taking a long time. Blah, I wrote about that on Hesterton's thread so I won't go on about it here.
The point is, I know nobody else IRL with this condition, and I am so grateful to the few other women out there who wrote about their experience pre and post-surgery in their blogs. Their writing was funny, intelligent, unpatronising, uncompromising. Without those blogs, I'd have no idea what to expect from my surgery, whether every little niggle post-op was 'normal' or not, or what my scars might look like in 6months or a year's time. It gave me hope that I can get through this and that there is life on the other side! 
I started writing my own blog when some of these bloggers asked me to write about my own experience of going through surgery and major rehab. Maybe it is a bit narcissistic - but it also helps me to write it all down, and then get on with my life. I get bored just writing about the 'woe-is-me' aspect, so I intersperse that with pictures of particularly nice cakes I have baked, too.
Clearly, that's boring to lots of people, but if somebody on the other side of the world, who has been diagnosed with the same condition as me, finds my blog via Google and discovers that yes, life goes on and hey, you can still bake if you want to - then I'm happy with that. Most of the people who comment on my blog are people who have found me whilst hunting for information about this condition. So for me, it's been a good way of finding new people who are in the same boat as me, and sharing information and / or coping strategies in relation to a condition about which many GPs and even consultants are not particularly well-informed.
I also quite like looking at those blogs full of pretty clothes and shoes. 